Predicting Gas Hydrates Location And Quantities Just Got Easier

Bhatnagar, a chemical engineering doctoral student in the lab of George Hirasaki, has expressed the results of complex computer models in terms of dimensionless groups or variables that make it much easier to predict where gas hydrates will form and in what quantity.

"Gaurav's accomplishments have earned him a substantial reputation as a quality researcher," said Hirasaki, the A.J. Hartsook Professor of Chemical and Biomolecular Engineering. "Whereas previous models required about a dozen parameters and typically characterized hydrates only for a particular set of conditions, Gaurav's models are made general by combining multiple variables into dimensionless groups or variables. For example, he was able to create a system that combined hundreds of simulations into just two composite plots with dimensionless variables."

The quality of Bhatnagar's work hasn't gone unnoticed. In 2006, he won the Society of Petroleum Engineers' (SPE) Gulf Coast Regional Student Paper Contest, the SPE's International Student Paper Contest and an Outstanding Student Paper Award from the American Geophysical Union (AGU). The latter award will be presented at the AGU's May meeting in Acapulco, Mexico, where Bhatnagar is slated to present his latest findings.

In his new research, Bhatnagar's developed a way to use a single variable – depth of the sulfate-methane interface– as a shorthand measure to effectively predict where hydrates will occur and the quantity of the hydrate accumulation.

"Sulfate-methane interface depth is a standard measure that can be easily calculated from shallow sediment cores," said Bhatnagar. "We have shown that this sulfate-methane interface can be directly used as a proxy for quantifying the amount of gas hydrate in the sediments. Sulfate in marine sediments can be measured more accurately than other geochemical data and may be a better indicator of the presence of gas hydrates. Moreover, sulfate data can be obtained from shallow cores, which also avoids the complications arising from drilling through hydrate layers. "

Methane hydrates form under the ocean floor, where temperatures plunge and the weight of the ocean exerts thousands of pounds per square inch, trapping methane gas inside ice-like crystals tens to hundreds of meters below the seafloor. Dubbed the "ice that burns," hydrates release gaseous methane when they melt. It's estimated that there are as much as 20 trillion tons of methane locked away in gas hydrates on the outer edges of the Earth's continents, and the Department of Energy has estimated that the commercial development of just 1 percent of the U.S.’s hydrate resources would more than double the nation’s proved gas reserves.

Bhatnagar's research is supported by Rice's Shell Center for Sustainability and by a Kobayashi Graduate Fellowship. He plans to graduate in December and has already accepted an offer to work in the gas hydrate group at Houston-based Shell Oil.